A Hybrid EIGamal - AES Based Secure Image Encryption System

Abstract: The rapid progress of digital communication has increased the need for secure image protection mechanisms in applications such as healthcare, cloud storage, surveillance, military communication, and multimedia systems. Since image data contains high redundancy and strong correlation between neighbouring pixels, traditional text-oriented encryption techniques alone are not always sufficient for efficient and secure image protection. This paper presents a hybrid image encryption framework that combines the Advanced Encryption Standard (AES) and the ElGamal public- key cryptosystem to achieve both computational efficiency and secure key management. In the proposed model, AES is used to encrypt image data because of its fast processing capability, while ElGamal is employed to protect the AES secret key during transmission. The system also integrates statistical and performance evaluation modules to validate encryption strength. Security analysis is performed using entropy evaluation, histogram analysis, NPCR, UACI, key sensitivity testing, and noise attack simulation. Experimental observations show that the encrypted images exhibit strong randomness, uniform pixel distribution, and high resistance against differential and statistical attacks. The framework also demonstrates efficient encryption and decryption performance for different image sizes. The proposed hybrid approach provides a practical and reliable solution for secure image transmission and storage applications.

Keywords: Image Encryption, AES, ElGamal, Hybrid Cryptography, Secure Image Transmission, NPCR, UACI, Entropy Analysis